Effects of nicorandil on QT prolongation and myocardial damage caused by citalopram in rats

Citalopram is a selective serotonin re-uptake inhibitor (SSRI) antidepressant; it exhibits the greatest cardiotoxic effect among SSRIs. Citalopram can cause drug-induced long QT syndrome (LQTS) and ventricular arrhythmias. We investigated the protective effect of nicorandil, a selective mitochondrial KATP (mito-KATP) channel opener, on LQTS and myocardial damage caused by citalopram in male rats. In a preliminary study, we determined that the minimum citalopram dose that prolonged the QT interval was 102 mg/kg injected intraperitoneally. For the main study, rats were divided randomly into five experimental groups: untreated control, normal saline + citalopram, nicorandil + citalopram, 5-hydroxydecanoate (5-HD) + citalopram, 5-HD + nicorandil + citalopram. Biochemical and histologic data from blood and heart tissue samples from six untreated control rats were evaluated. Electrocardiographic parameters including QRS duration, QT interval, corrected QT interval (QTc) and heart rate (HR) were assessed, and biochemical parameters including malondialdehyde, reduced glutathione, glutathione peroxidase, superoxide dismutase were measured. We also performed histomorphologic and immunohistochemical examination of heart tissue. Citalopram prolonged QT-QTc intervals significantly and increased significantly the histomorphologic score and proportion of apoptotic cells, but produced no differences in the oxidant and antioxidant parameters. Nicorandil did not prevent citalopram induced QT-QTc interval prolongation and produced no significant changes in oxidant and antioxidant parameters; however, it did reduce histologic damage and apoptosis caused by citalopram.

Effect of the selective mitochondrial KATP channel opener nicorandil on the QT prolongation and myocardial damage induced by amitriptyline in rats

OBJECTIVES

The aim of this study is to evaluate the protective effect of nicorandil, a selective mitochondrial KATP channel opener, on QT prolongation and myocardial damage induced by amitriptyline.

METHODS

The dose of amitriptyline (intraperitoneal, i.p.) that prolong the QT interval was found 75 mg/kg. Rats were randomized into five groups the control group, amitriptyline group, nicorandil (selective mitochondrial KATP channel opener, 3 mg/kg i.p.) + amitriptyline group, 5-hdyroxydecanoate (5-HD, selective mitochondrial KATP channel blocker, 10 mg/kg i.p.) + amitriptyline group and 5-HD + nicorandil + amitriptyline group. Cardiac parameters, biochemical and histomorphological/immunohistochemical examinations were evaluated. p < 0.05 was accepted as statistically significant.

KEY FINDINGS

Amitriptyline caused statistically significant prolongation of QRS duration, QT interval and QTc interval (p < 0.05). It also caused changes in tissue oxidant (increase in malondialdehyde)/anti-oxidant (decrease in glutathione peroxidase) parameters (p < 0.05), myocardial damage and apoptosis (p < 0.01 and p < 0.001). While nicorandil administration prevented amitriptyline-induced QRS, QT, QTc prolongation (p < 0.05), myocardial damage and apoptosis (p < 0.05), it did not affect the changes in oxidative parameters (p > 0.05).

CONCLUSIONS

Our results suggest that nicorandil, a selective mitochondrial KATP channel opener, plays a protective role in amitriptyline-induced QT prolongation and myocardial damage. Mitochondrial KATP channel opening and anti-apoptotic effects may play a role in the cardioprotective effect of nicorandil.

The Effects of Irbesartan and Spironolactone in Prevention of Peritoneal Fibrosis in Rats

Background

Bacterial peritonitis episodes may disturb the functional and histological integrity of the peritoneum in peritoneal dialysis patients. The renin–angiotensin–aldosterone system may have fibrotic effects on the peritoneum.

Objective

To study the effects of an angiotensin II receptor antagonist (irbesartan) and an aldosterone antagonist (spironolactone) in the prevention of peritoneal fibrosis in a rat model of bacterial peritonitis.

Methods

40 Wistar rats were randomized into 5 groups: bacteria (B), bacteria–irbesartan (BI), bacteria–spironolactone (BS), bacteria–irbesartan–spironolactone (BIS), and control (C) groups. The C group received only dextran beads (Cytodex; Sigma Chemicals, St Louis, Missouri, USA); the others were given bacteria and dextran beads intraperitoneally. Irbesartan and/or spironolactone were given to 3 groups: BI, BS, and BIS. On the eighth day, the rats were sacrificed, peritoneal adhesion was quantified, and peritoneal tissue sections were evaluated histologically.

Results

The peritoneal total adhesion score was significantly higher in the B group than in the BI, BIS, and C groups ( p < 0.01). Mean peritoneal thickness, mean inflammation score, and mean fibrosis score were significantly higher in the B group in comparison to the C group ( p < 0.05). Mean peritoneal thickness of all treatment groups was significantly lower than the B group ( p < 0.05). Serum transforming growth factor beta-1 level was significantly higher in the B group than in the BI, BS, and C groups ( p < 0.05).

Conclusion

Irbesartan and spironolactone seem to decrease the extent of peritoneal injury caused by bacterial peritonitis.

Artificial Neural Network Approach in Laboratory Test Reporting: Learning Algorithms

OBJECTIVES

In the field of laboratory medicine, minimizing errors and establishing standardization is only possible by predefined processes. The aim of this study was to build an experimental decision algorithm model open to improvement that would efficiently and rapidly evaluate the results of biochemical tests with critical values by evaluating multiple factors concurrently.

METHODS

The experimental model was built by Weka software (Weka, Waikato, New Zealand) based on the artificial neural network method. Data were received from Dokuz Eylül University Central Laboratory. "Training sets" were developed for our experimental model to teach the evaluation criteria. After training the system, "test sets" developed for different conditions were used to statistically assess the validity of the model.

RESULTS

After developing the decision algorithm with three iterations of training, no result was verified that was refused by the laboratory specialist. The sensitivity of the model was 91% and specificity was 100%. The estimated κ score was 0.950.

CONCLUSIONS

This is the first study based on an artificial neural network to build an experimental assessment and decision algorithm model. By integrating our trained algorithm model into a laboratory information system, it may be possible to reduce employees' workload without compromising patient safety.

Effect of day/night administration of three different inhalational anesthetics on melatonin levels in rats

The nocturnal peak of melatonin can be altered after anesthesia and surgery. We aimed to examine the melatonin levels during the day and night after anesthesia with three commonly used inhalational anesthetics. Forty-eight male Wistar albino rats were randomized into eight groups. Rats were administered anesthesia between 7:00 am and 1:00 pm (day groups) or 7:00 pm and 1:00 am (night groups) for 6 hours. At the end of the anesthesia, blood samples were collected for assessing melatonin levels. Mean values of melatonin levels after 6 hours of anesthesia during daytime were 43.17±12.95 for control, 59.79±27.83 for isoflurane, 50.75±34.28 for sevoflurane and 212.20±49.56 pg/mL for desflurane groups. The night groups' mean melatonin levels were 136.12±33.20 for control, 139.85±56.29 for isoflurane, 117.48±82.39 for sevoflurane and 128.70±44.63 pg/mL for desflurane groups. Desflurane anesthesia between 7:00 am and 1:00 pm significantly increased melatonin levels (p<0.001). Sevoflurane and desflurane anesthesia between 7:00 pm and 1:00 am decreased the melatonin levels but there were no significant differences (p=0.904 and p>0.99, respectively). Isoflurane anesthesia did not significantly change melatonin levels during day or night (p=0.718 and p>0.99, respectively). Our results demonstrate that during daytime desflurane anesthesia can alter melatonin levels. Altered melatonin rhythm following inhalational anesthesia can be related to sleep disorders observed after anesthesia.

A multicenter nationwide reference intervals study for common biochemical analytes in Turkey using Abbott analyzers

BACKGROUND

A nationwide multicenter study was organized to establish reference intervals (RIs) in the Turkish population for 25 commonly tested biochemical analytes and to explore sources of variation in reference values, including regionality.

METHODS

Blood samples were collected nationwide in 28 laboratories from the seven regions (≥400 samples/region, 3066 in all). The sera were collectively analyzed in Uludag University in Bursa using Abbott reagents and analyzer. Reference materials were used for standardization of test results. After secondary exclusion using the latent abnormal values exclusion method, RIs were derived by a parametric method employing the modified Box-Cox formula and compared with the RIs by the non-parametric method. Three-level nested ANOVA was used to evaluate variations among sexes, ages and regions. Associations between test results and age, body mass index (BMI) and region were determined by multiple regression analysis (MRA).

RESULTS

By ANOVA, differences of reference values among seven regions were significant in none of the 25 analytes. Significant sex-related and age-related differences were observed for 10 and seven analytes, respectively. MRA revealed BMI-related changes in results for uric acid, glucose, triglycerides, high-density lipoprotein (HDL)-cholesterol, alanine aminotransferase, and γ-glutamyltransferase. Their RIs were thus derived by applying stricter criteria excluding individuals with BMI >28 kg/m2. Ranges of RIs by non-parametric method were wider than those by parametric method especially for those analytes affected by BMI.

CONCLUSIONS

With the lack of regional differences and the well-standardized status of test results, the RIs derived from this nationwide study can be used for the entire Turkish population.

Diverse glial cell line-derived neurotrophic factor (GDNF) support between mania and schizophrenia: a comparative study in four major psychiatric disorders

BACKGROUND

Brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) have essential roles in synaptic plasticity which is involved in pathogenesis and treatment of psychiatric disorders. However, it is not clear whether they act simultaneously during illness states in major psychiatric disorders.

METHODS

BDNF and GDNF serum levels were measured concomitantly by enzyme-linked immunosorbent assay (ELISA) method in 171 patients diagnosed with schizophrenia (n=33), bipolar disorder-manic episode (n=39), bipolar/unipolar depression (n=64, 24/40) and obsessive-compulsive disorder (n=35) according to DSM-IV, and 78 healthy volunteers. SCID-I and SCID non-patient version were used for clinical evaluation of the patients and healthy volunteers, respectively. Correlations between the two trophic factor levels, and illness severity scores, duration of illness and medication dosages were studied across different illnesses.

RESULTS

While patients had equally lower BDNF levels in all diagnoses, GDNF levels were significantly higher in mania and lower in schizophrenia compared to healthy controls. BDNF levels were negatively correlated to illness severity scores in affective episodes (mania and depression). Longer duration of illness (>5 years) had an impact on lower GDNF levels in schizophrenia. BDNF levels and antipsychotic drug dosages in schizophrenia, and GDNF levels and antidepressant drug dosages in obsessive-compulsive disorder were positively correlated.

CONCLUSION

Our data confirmed the evidence of equally deficient neuronal support by BDNF in all major psychiatric illnesses, but suggested a diverse glial functioning between schizophrenia and mania.

New generation IQ-200 automated urine microscopy analyzer compared with KOVA cell chamber

OBJECTIVE

The examination of the urine remains to be one of the most commonly performed tests in laboratory practice. Currently, laboratories also need to accredit their urine diagnostics by comparing their measurement methods to acceptable references. In this study we compared particle counts obtained by new generation automated technique, image capture analysis (IQ-200) with those of a standardized chamber counts.

DESIGN AND METHODS

The same 258 urine samples from different departments of a hospital assayed by IQ-200 were analyzed in parallel with the KOVA cell chamber system. Clinically significant discrepancy results (positive vs. negative) for red blood cell (RBC) and white blood cell (WBC) were also compared with those obtained by dipstick testing.

RESULTS

There was a good agreement between the automated system and sediment microscopy for RBCs, WBCs, and squamous epithelial cells (SCs) (r=0.90; r=0.80; r=0.72, respectively: P<0.001). The IQ-200 was more sensitive for determining RBCs, WBCs, and SCs than other formed elements.

CONCLUSIONS

IQ-200 can perform accurate quantification of microscopic element in urine. However, automated techniques are not completely free of error. Therefore, by adopting an appropriate algorithm and combining the results with stript analysis and other laboratory tests allows further reduction of clinically important errors.

Serum transforming growth factor-beta 1 levels in normoalbuminuric and normotensive patients with type 2 diabetes. Effect of metformin and rosiglitazone

OBJECTIVE

a)To determine serum Transforming Growth Factor-beta 1 (TGF-beta 1) levels in patients with type 2 diabetes who do not have diabetes related complications and in healthy controls, b) to evaluate the effects of metformin and rosiglitazone on TGF-beta 1 levels.

DESIGN

In the washout period, 61 patients with Fasting Plasma Glucose levels (FPG) higher than 140 mg/dl, Postprandial Glucose (PPG) levels higher than 180 mg/dl and A1c levels exceeding 6.5% were treated with glimperide. After 4 weeks, 39 of these patients were randomised to receive either metformin or rosiglitazone for 12 weeks. Thirty healthy controls were also studied.

RESULTS

There were no significant differences with regard to age, gender, body weight and BMI between patients and healthy controls. Type 2 diabetics had higher waist circumference, FPG, total cholesterol, LDL-cholesterol and triglyceride levels. Baseline TGF-beta 1 levels in diabetics were higher than in controls (29.84+/-7.04 ng/ml vs 11.37+/-4.06 ng/ml, p<0.001). Metformin or rosiglitazone did not significantly modify the TGF-beta 1 levels. In a multiple regression analysis FPG was the only variable that was significantly associated with plasma TGF-beta 1 levels.

CONCLUSION

The elevated levels of TGF-beta 1 in subjects with type 2 diabetes possibly indicate a tendency for renal and endothelial damage in such patients. The association of TGF-beta 1 with FPG possibly links poor diabetic control to vascular damage, leading to diabetic complications. Lack of changes in the levels of TGF-beta 1 after therapy may reflect inadequate therapy duration.

The effects of irbesartan and spironolactone in prevention of peritoneal fibrosis in rats

BACKGROUND

Bacterial peritonitis episodes may disturb the functional and histological integrity of the peritoneum in peritoneal dialysis patients. The renin-angiotensin-aldosterone system may have fibrotic effects on the peritoneum.

OBJECTIVE

To study the effects of an angiotensin II receptor antagonist (irbesartan) and an aldosterone antagonist (spironolactone) in the prevention of peritoneal fibrosis in a rat model of bacterial peritonitis.

METHODS

40 Wistar rats were randomized into 5 groups: bacteria (B), bacteria-irbesartan (BI), bacteria-spironolactone (BS), bacteria-irbesartan-spironolactone (BIS), and control (C) groups. The C group received only dextran beads (Cytodex; Sigma Chemicals, St Louis, Missouri, USA); the others were given bacteria and dextran beads intraperitoneally. Irbesartan and/or spironolactone were given to 3 groups: BI, BS, and BIS. On the eighth day, the rats were sacrificed, peritoneal adhesion was quantified, and peritoneal tissue sections were evaluated histologically.

RESULTS

The peritoneal total adhesion score was significantly higher in the B group than in the BI, BIS, and C groups (p < 0.01). Mean peritoneal thickness, mean inflammation score, and mean fibrosis score were significantly higher in the B group in comparison to the C group (p < 0.05). Mean peritoneal thickness of all treatment groups was significantly lower than the B group (p < 0.05). Serum transforming growth factor beta-1 level was significantly higher in the B group than in the BI, BS, and C groups (p < 0.05).

CONCLUSION

Irbesartan and spironolactone seem to decrease the extent of peritoneal injury caused by bacterial peritonitis.

Comparison and evaluation of two C-reactive protein assays based on particle-enhanced immunoturbidimetry

The use of C-reactive protein (CRP) assays is increasing for a wide range of clinical conditions, and consequently the analytical performance requirements for CRP assays are also changing. For this reason, manufacturers have been developing CRP assays based on different methodologies to provide both high sensitivity and a wide measuring range. However, it is questionable whether these methods can meet the desired requirements for CRP assays. CRP Latex on the Cobas Integra 400 and CRP Tina-quant Latex on the Modular Analytics-P were evaluated in terms of detection limit, linearity, intra- and interassay precision, and comparability with 268 patient samples. The intra- and interassay precision of the two methods was <4.1% in the three pools with CRP concentrations ranging from 6.9 to 215 mg/L, and >10% in the pool with concentrations of approximately 0.60 mg/L. The detection limits for CRP Latex and Tina-quant Latex were 0.20 and 0.22 mg/L, respectively. Both methods were linear up to 215 mg/L. There was a good agreement between the two assays, except for a scattering at concentrations near the detection limits. Deming regression analysis for CRP Latex (x-axis) and Tina-quant Latex (y-axis) yielded a slope of 1.067+/-0.018, an intercept of -0.148+/-0.358, and an S(y/x) of 5.10 (r=0.996, P<0.0001). The two assays gave comparable results. Low precision was determined for both assays, except for the low pool with a concentration of approximately 0.60 mg/L. We concluded that both of these assays should be improved to meet high-sensitivity criteria.

Influences of Acute and Chronic Aerobic Exercise on the Plasma Homocysteine Level

BACKGROUND AND AIMS

Elevated plasma homocysteine (PH) levels have been identified as a risk factor for cardiovascular diseases. The aims of this study were to investigate the influences of submaximal acute aerobic exercise and aerobic training on PH levels and lipid profiles.

METHODS

69 volunteer subjects (21.12 +/- 2.08 years) were randomized to three groups as acute, training and control groups. Examination and blood samples were collected before and immediately after exercise in the acute group and before and 6 weeks later in the training and control groups.

RESULTS

A significant increase in PH concentration was recorded immediately after aerobic exercise, compared with baseline values (p = 0.001). Although, in the training group, total cholesterol (p = 0.00) and LDL cholesterol (p = 0.001) decreased significantly after training, no significant changes in PH concentration, HDL cholesterol (p = 0.087) and triglyceride (p = 194) levels were found.

CONCLUSIONS

It can be said that the PH level increases following submaximal acute aerobic exercise, but does not alter after submaximal aerobic training due to training duration or intensity. Therefore, submaximal aerobic training decreases lipid profiles independent of the PH level.

The inappropriate use of HbA1c testing to monitor glycemia: is there evidence in laboratory data?

RATIONALE, AIMS AND OBJECTIVES

Diabetes is a chronic illness and have relatively high prevalence. Glycemic control is fundamental to the management of diabetes. Hemoglobin A1c (HbA1c) is a commonly used laboratory test to monitor glycemia and to manage diabetes. This study aimed to assess the appropriateness of the frequency of HbA1c test order with respect to the commonly approved guidelines for monitoring glycaemia of patients.

METHODS

To assess the rate of inappropriate test orders, laboratory records of HbA1c tests ordered between 2002 and 2004 were evaluated. Inappropriate orders were defined as any order for a given patient that takes place within a 29- or 89-day-period following the previous HbA1c order. The effects of various parameters, like ordering clinics, the first HbA1c level, or the on-line availability of test results on test ordering were evaluated.

RESULTS

Evaluation of test intervals showed that 10.3% of all orders and 33.8% of the inpatients' orders were performed within 29 days, 35.5% of all orders and 55% of the inpatients' orders were within 89 days.

CONCLUSIONS

Inappropriate laboratory utilization of HbA1c testing is very common especially in the inpatient clinics. We think that the application of the guidelines may decrease unnecessary health expenditure.

Effects of N-acetylcysteine on radiocontrast nephropathy in rats

OBJECTIVE

N-acetylcysteine (NAC) has yielded some promising results recently in the prevention of radiocontrast nephropathy (RCN). In this study, the structural and functional effects of NAC on RCN were analyzed.

MATERIAL AND METHODS

Twenty-eight Wistar rats were randomized into four groups, as follows: Group 1, controls; Group 2, contrast; Group 3, contrast+NAC; and Group 4, NAC. All rats were deprived of water for 24 h and then contrast medium (ioxoglate; 10 ml/kg) was administered to Groups 2 and 3. NAC (50 mg/kg) was introduced enterally to Groups 3 and 4 at a dose of 50 mg/kg in 0.5 ml of distilled water, in four sequential doses 12h apart, starting after 12?h of water deprivation. After 4 days, rats were sacrificed. Creatinine clearance was calculated. The malondialdehyde (MDA) level was quantified in tissue samples. Slides stained with hematoxylin-eosin and periodic acid-Schiff were examined by means of light microscopy. Each tubular cross-section from all images was scored as either mild (preserved brush border, no necrosis), moderate (loss of brush border, no necrosis) or severe (loss of brush border accompanied by necrosis) and the frequencies of these lesion severities were compared.

RESULTS

Mean baseline serum creatinine levels and creatinine clearances were similar in all groups. Mean serum creatinine level increased significantly only in Group 2 (0.6+/-0.1 vs 0.7+/-0.2 mg/dl; p<0.05). Tissue MDA levels were similar in all groups. Moderate (13.8%+/-1.5% vs 42%+/-1.4%; p<0.05) and severe (0% vs 40%+/-2.1%; p<0.05) lesions were significantly more frequent in Group 2 compared to Group 1. The frequency of severe lesions in Group 3 was found to be halved compared to that in Group 1 (40%+/-2.1% vs 20.2%+/-0.86%; p<0.05).

CONCLUSION

NAC protects the kidneys following exposure to contrast medium as it decreased the severity of tubular lesions in rats.

Effects of estrogen, raloxifene, and hormone replacement therapy on serum C-reactive protein and homocysteine levels

OBJECTIVES

To investigate the effects of conjugated equine estrogen (CEE), CEE plus medroxyprogesterone acetate (MPA), CEE plus Nomegestrol acetate (NA), and raloxifene on serum high sensitivity C-reactive protein (hs-CRP) and homocysteine (Hcy) levels in healthy postmenopausal women.

MATERIALS

One hundred seven healthy postmenopausal women were recruited in a prospective, randomized, and placebo-controlled 6 months study. Of these, 18 were hysterectomized and received daily oral 0.625 mg CEE. Eighty nine non-hysterectomized women were randomly allocated to one of four groups: a group (22 patients) treated with CEE, 0.625 mg/daily plus MPA 2.5 mg/daily; a group (22 patients) treated with CEE, 0.625 mg/daily plus NA 5 mg/daily; a group (23 patients) treated with raloxifene hydrochloride, 60 mg once daily; and a placebo group (22 patients). Hcy and hs-CRP were measured at baseline and at 3 and 6 months.

RESULTS

CEE (20%, P=0.03) and CEE+MPA (59%, P=0.006) increased serum hs-CRP levels significantly, whereas CEE+NA decreased serum hs-CRP by 25% (P=0.01). Raloxifene had no significant effect on serum hs-CRP levels during and after the treatment. In all active treatment groups serum Hcy levels decreased significantly compared to baseline and placebo.

CONCLUSIONS

Conjugated equine estrogen, hormone replacement therapies, and raloxifene lower serum Hcy levels to a comparable extent in postmenopausal women. Hs-CRP, as a cardiovascular risk factor, is not influenced by raloxifene, whereas CEE and CEE plus MPA significantly increase hs-CRP levels. Treatment with CEE plus NA reduces serum hs-CRP levels.

Is awareness of its risk enough to stop people from smoking?

A questionnaire to elicit information about smoking habits and knowledge of the risks of smoking was administered to 100 students (53 men and 47 women) in the graduating class of 1993 at the Cerrahpaşa Medical School of Istanbul. Forty-three percent of the men and 27% of the women students were smokers. All but one of the 100 students were aware that smoking is a risk factor for both lung and laryngeal cancers, and 44% of the smokers believed that cessation of smoking by the smoking population could decrease the incidence of lung cancers to less than half of its present level. These data suggest that awareness of the risks of smoking is not enough to motivate smokers to quit, even when they are young physicians. Of the nonsmokers, 87.5% indicated that they would attempt to restrain their younger siblings from smoking, whereas the corresponding figure for smokers was 58.3%. The smokers and the nonsmokers answered two of the questions on the questionnaire significantly differently. Thirty-six percent of the mothers of the nonsmokers and 31% of their siblings were also smokers, whereas the corresponding figures for the nonsmokers were 18% and 13% (half of the fathers in both groups smoked). Thus, family and the environment appear to influence smoking behavior. Successful modification of smoking habits will necessitate more education of the general public.